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ABSTRACT: The capacity of antibodies to interfere with Plasmodium falciparum growth in in vitro cultures is considered to reflect some of their potential protective effects in vivo. Almost all previous analyses of antibody mediated inhibition of parasite growth in vitro were performed with different laboratory strains of P. falciparum. This study was performed to investigate if the long-term culturing of parasites has any effect on their susceptibility to such growth inhibition. The growth inhibitory effects of human antibodies to the vaccine candidate antigens Pf155/RESA and Pf332 on fresh field isolates from children in Burkina Faso were analysed and compared with their effect on an established laboratory strain of the parasite. Although there was variation in the inhibition titres between different isolates tested against one antibody preparation, the differences in inhibition capacity for the three different antibodies were highly significant. No correlation was found between serum levels of anti-Pf155/RESA or -Pf332 antibodies and sensitivity of the corresponding parasite isolates to antibody mediated growth inhibition.
Parasite Immunology 07/1999; 21(6):331-4. · 2.60 Impact Factor
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ABSTRACT: Antibodies to a non-repeat region of the Plasmodium falciparum antigen Pf155/RESA were investigated for their capacity to inhibit parasite cytoadherence to melanoma cells and parasite growth in vitro. The activities of these antibodies were studied since the target region in Pf155/RESA includes a cytoadherence-related motif also found in loop 3 and 7 of human erythrocyte band 3 protein. Overlapping multiple antigen peptides (MAPs) together spanning residues 199-220 of Pf155/RESA were used to raise antibodies in rabbits. Analysis of the fine specificity of these antibodies revealed that antibodies raised against largely overlapping sequences displayed highly different specificity patterns. Similarly, striking differences were seen when analysing the biological effect of antibodies to these MAPs. Antibodies to the cytoadherence-related motif of Pf155/RESA, as well as antibodies raised against a MAP based on a corresponding band 3 motif, inhibited cytoadherence but not parasite growth. In contrast, antibodies to sequences adjacent to the Pf155/RESA cytoadherence motif inhibited parasite growth in vitro but had no effect on cytoadherence.
Parasitology 10/1998; 117 ( Pt 3):209-16. · 2.96 Impact Factor
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ABSTRACT: Antibodies to a non-repeat region of the
Plasmodium
falciparum antigen Pf155/RESA were investigated
for their capacity
to inhibit parasite cytoadherence to melanoma cells and parasite growth
in
vitro. The activities of these antibodies were
studied since the target region in Pf155/RESA includes a
cytoadherence-related motif also found in loop 3 and 7 of human
erythrocyte band 3 protein. Overlapping multiple antigen peptides (MAPs)
together spanning residues 199–220 of
Pf155/RESA were used to raise antibodies in rabbits. Analysis of
the fine specificity of these antibodies revealed that
antibodies raised against largely overlapping sequences displayed
highly different specificity patterns. Similarly, striking
differences were seen when analysing the biological effect of antibodies
to these MAPs. Antibodies to the cytoadherence-related motif
of Pf155/RESA, as well as antibodies raised against a MAP based on
a corresponding band 3 motif, inhibited
cytoadherence but not parasite growth. In contrast, antibodies to sequences
adjacent to the Pf155/RESA cytoadherence
motif inhibited parasite growth in
vitro but had no effect on
cytoadherence.
Parasitology 08/1998; 117(03):209 - 216. · 2.96 Impact Factor
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ABSTRACT: Immune responses to the repeat regions of the Plasmodium falciparum antigen Pf155/RESA have been extensively studied, and antibodies to the repeats are known to interfere with parasite growth both in vitro and in vivo. Less is known with regard to the effect on parasites of antibodies to the nonrepeat regions of the antigen. In the present study, rabbits were immunized with synthetic peptides corresponding to three different nonrepeated sequences of antigen Pf155/RESA. The reactivity of the antibodies with the particular peptides was analyzed by enzyme-linked immunosorbent assay (ELISA) and that with the parasite antigen, by immunoblotting and immunofluorescence. Although all antisera reacted strongly with the corresponding synthetic peptides, they reacted only weakly with full-length Pf155/RESA in either of the methods used. The specificity of the antibodies for Pf155/RESA was confirmed by their failure to stain Pf155/RESA-deficient parasites in erythrocyte membrane immunofluorescence, a method mainly detecting this antigen. Antibodies to the nonrepeat sequences also efficiently inhibited the merozoite invasion in vitro of Pf155/RESA+ parasites. However, these antibodies also inhibited Pf155/RESA-deficient parasites, indicating the presence of an antigen exhibiting a high degree of homology with Pf155/RESA. The results indicate that nonrepeat sequences of Pf155/RESA are immunogenic and may serve as targets for parasite-neutralizing antibodies, and, thus, the potential of the antigen as a vaccine candidate is emphasized.
Parasitology Research 07/1998; 84(6):485-91. · 2.15 Impact Factor
